As usual, Dr. Craven calls on Colin the day after the tantrum. He usually finds Colin white and ready to set off into hysterics again, but Mrs. Medlock assures him that Colin is different today, thanks to the "plain sour-faced child" who gave Colin a taste of his own medicine the night before. Dr. Craven is astonished to see Colin and Mary giggling and looking at a book. They stop as soon as they see the doctor. Colin grandly says that he's better and wants to go outside, which startles Dr. Craven. He also insists that the nurse won't go; Mary will accompany him instead. This all concerns Dr. Craven as he does stand to inherit Misselthwaite if Colin dies, but he has no interest in actively sabotaging Colin.
Notice that though Dr. Craven isn't entirely sure he wants Colin to recover, his thoughts aren't so negative as to wish Colin ill. This suggests that Dr. Craven is already somewhat versed in the power of positive thinking, or at least understands the power of not wishing someone ill. When Dr. Craven is surprised to see Colin and Mary enjoying themselves together, it indicates that he's never considered before how good it might be for Colin to have a friend.
When Dr. Craven hears that Dickon is the one who will push Colin's wheelchair, he visibly relaxes. He laughs at Mary when she speaks to him in Yorkshire, and she replies coldly that she's learning Yorkshire like she would French. When Dr. Craven asks Colin if he took his medicine, Colin admits he didn't. However, as Dr. Craven starts to remind Colin of the things he needs to remember, Colin says he wants to forget the things that make him want to scream, as forgetting makes him feel better. Dr. Craven leaves soon after and speaks briefly with Mrs. Medlock about how Mrs. Sowerby has said that it's good for Colin and Mary to know each other. They discuss that Mrs. Sowerby believes that children teach each other that a single person doesn't own the whole world.
Mary's unwillingness to politely engage with the doctor suggests that she doesn't trust him yet to actually have Colin's best interests at heart, especially after hearing the doctor remind Colin to remember how ill he is. The adults' conference in the hallway again situates Mrs. Sowerby as an expert on child development, as she knows the best way to guide children towards independence and adulthood. Specifically, they show that Mrs. Sowerby believes in the ability of children to act as mirrors for each other, just as Mary and Colin are doing.
Colin sleeps all through the night and wakes refreshed in the morning. Mary arrives minutes later, smelling of the outdoors and with the news that spring has truly arrived. Colin laughs and asks Mary to open the window so they can hear "golden trumpets." Mary throws open the window and instructs Colin to lie down and breathe deeply. She says that Dickon thinks that doing so will make him live forever, which intrigues Colin. Mary tells him about all the live things outside, especially the newborn lamb that Dickon saved three days ago. The nurse enters, confirms that Colin actually wants the window open, and goes away to order two breakfasts.
Colin's good night of sleep can be attributed to his excitement at getting to go outside; now that he's thinking good thoughts and is thinking kindly about nature, he naturally feels better. The mention of "golden trumpets" suggests that the natural world is just as wondrous as the kind of paradise that exists within in the pages of the Bible, which reinforces the almost Edenic role that the secret garden is playing for the children.
When Colin and Mary receive their breakfast, Colin imperiously tells his nurse that Dickon and his creatures are going to visit and are to be brought right to him by Martha. The nurse is uncertain about the animals, but Colin says that Dickon is an animal charmer and the animals won't bite. As they eat, Mary says that Colin will start to get fatter if he keeps eating his breakfast.
Now that Mary has seen what an effect eating has had on her, she's ready to share that knowledge and possibility with Colin. This reminds the reader that one of the core tenets of the novel is that once a person learns valuable lessons from nature or from someone else, they must pass it on.
About ten minutes later, Colin and Mary hear Dickon's animals in the hallway. Martha shows Dickon in, accompanied by Soot, Captain, Nut, Shell, and the lamb. Colin stares in wonder but cannot speak. Dickon silently approaches and puts the lamb on Colin's lap. The lamb starts to nuzzle into Colin's robe, and Dickon explains that the lamb is hungry. He pulls out a bottle to feed it and as the lamb eats and falls asleep, tells Colin all about finding the lamb on the moor. The children all look at the gardening books, and Dickon points out which flowers are already growing in the garden. Colin vows to go outside and see the flowers.
Just as Mary's first real friend was the robin, Colin's first interaction with the outdoors comes in the form of these wild creatures. This suggests that animals like this are an easy entry into the outside world for someone like Mary or Colin who's never experienced either the joys of the natural world or a sense of camaraderie with another living being before. Specifically, when the lamb leads Colin to address Dickon, it shows that he's taking the same route as Mary to making friends with Dickon.